1. Field of the Invention
The present invention relates to an optical axis tilting device of a laser optical system.
2. Description of Related Art
It is known that an optical axis tilting device of a laser optical system has been used as a tilt gradient setting device in, for example, a rotary laser survey equipment. It is known that, as a control means configured to control a setting amount of a tilting angle relative to horizontal or vertical of an optical axis of the laser optical system, the conventional optical axis tilting device of the laser optical system employs an encoder in its feed screw mechanism to detect a rotation speed of the feed screw mechanism, or an encoder in its driving motor which rotatably drives the feed screw.
JP H6-26861A discloses an optical axis tilting device of such a technique, which tilts the laser optical system from a horizontal position or a vertical position by driving the feed screw mechanism.
Moreover, it is also known an optical axis tilting device in which a tilt gradient of an optical axis of a laser optical system is set by tilting the laser optical system relative to a tilt sensor and leveling the whole optical axis tilting device.
However, in such the conventional optical axis tilting device of the laser optical system, the angle setting accuracy of the rotary laser survey equipment mainly depends on the accuracy of the feed screw mechanism, as a result of an accumulated error due to repetitive drives of a feed screw part of the feed screw mechanism, or a wear due to repetitive drives of the feed screw part, or a distortion of the feed screw part due to aged deterioration, etc., feed error occurs and causes deviation in angle setting, and thus a problem arises in that it is difficult to ensure tilting accuracy of the optical axis of the laser optical system.